Packaging machine having an adjustable pneumatic/hydraulic drive

ABSTRACT

The invention relates to a packaging machine, wherein at least one tool can be displaced to a lowered or to a lifted position by means of a lifting system, the lifting station being driven by at least one adjustable pneumatic/hydraulic drive.

The present invention relates to a packaging machine, in which at least one tool can be displaced by way of a lifting system into a lowered and into a raised position, the lifting station having, as drive, at least one automatically controlled pneumatic/hydraulic drive.

Nowadays, foodstuffs are often packed in plastic packagings, in order to make them nonperishable. The packagings are produced and filled as a rule by way of a packaging machine which operates semicontinuously and in which first of all the packaging cavity is deep drawn from a film, is then filled with the material to be packaged and is subsequently sealed with a cover film. The packagings which are produced in this way are cut from one another in a final step. During the production of the packaging, tools, for example the deep drawing mold, the sealing tool and/or the cutting tool, have to be moved vertically, quite considerable forces occurring, in particular, during sealing and cutting. The abovementioned tools have often been driven by way of pneumatic cylinders because they are simple and favorable to handle.

It was the object of the present invention to make a packaging machine available which is quicker, produces less noise and has less wear than machines according to the prior art.

According to the invention, the object is achieved by way of a packaging machine, in which at least one tool can be displaced by way of a lifting station into a lowered and into a raised position, the lifting station having, as drive, at least one automatically controlled pneumatic/hydraulic drive.

It was certainly surprising to a person skilled in the art and not to be expected that said packaging machine operates substantially more quickly and causes less noise than packaging machines according to the prior art. Moreover, the packaging machine according to the invention is less intensive to maintain than the packaging machines of the prior art.

According to the invention, the packaging machine has an automatically controlled pneumatic and/or hydraulic drive as drive for at least some of the tools which are present in it. Said pneumatic and/or hydraulic drive has a cylinder and a working rod. The cylinder or the rod is connected directly or indirectly to the tool. The cylinder and the rod can be connected fixedly or movably to the frame of the packaging machine or to the underlying surface, on which the packaging machine stands. Since the pneumatic and/or hydraulic drive is automatically controlled, the travel, the speed and/or the acceleration of the working rod and/or the cylinder are/is automatically controlled. Accordingly, the respective tool covers a very defined travel and the speed is automatically controlled at every instant of the travel, the speed not being constant. For example, it is possible as a result that the tool which is driven by the pneumatic and/or hydraulic drive covers the greatest part of its travel at a very high speed and moves gently into its end position.

The pneumatic and/or hydraulic drive can drive any desired mechanism, for example a crank mechanism, a cam mechanism or a linkage and a combination of said mechanism types. In one preferred embodiment of the packaging machine according to the invention, the pneumatic and/or hydraulic drive drives a toggle lever system which in turn brings about the up and down movement of the respective tools.

In the context of the invention, a tool is every tool which serves to produce a packaging and which has to be moved up and down. For example, the tool is a deep drawing mold, a sealing tool and/or a cutting tool. In the context of the invention, a tool can be situated below and/or above the film web, from which the packaging cavity is produced. A pneumatic and/or hydraulic drive can move both the lower tool and the upper tool of a workstation at the same time or one after another.

The pneumatic and/or hydraulic drive can be controlled in every way known to a person skilled in the art. The pressure of the pneumatic and/or hydraulic drive is preferably regulated. In phases, in which the pneumatic and/or hydraulic drive is to move quickly, a high pressure therefore prevails which is then reduced, for example, before an end position is reached.

The pneumatic and/or hydraulic drive preferably has an absolute travel transmitter, with the result that, in particular, the position of that end of the working rod which faces away from the drive cylinder and therefore the position of the tool are known precisely at all times to a controller of the packaging machine according to the invention. This signal is used to regulate the movement of the tool. This regulation not only permits the tool to be displaced between two fixed end points, but rather for it to be possible for the raised and lowered positions to be set as desired. Furthermore, this drive makes it possible for the speed at which the respective tool is moved between the two positions to be automatically controlled in a targeted manner at any instant.

In the context of the invention, a packaging machine is not only a thermoforming machine, in which the packaging cavity is produced by deep drawing and is then filled and is sealed with a cover film, but also what is known as a tray sealer, in which packaging cavities which have already been preformed are filled with a material to be packaged and are subsequently sealed with a packaging film. Furthermore, in the context of the invention, a packaging machine is also what is known as a tray former, in which only packaging cavities are deep drawn from a film and are subsequently cut from one another.

In the following text, the invention will be explained using FIGS. 1 and 6. These explanations are only by way of example.

FIG. 1 shows the principle construction of a deep drawing packaging machine.

FIG. 2 shows a side view of a workstation with a toggle lever system in a raised position.

FIG. 3 shows a front view of a workstation with a toggle lever system in a raised position.

FIG. 4 shows a plan view of a workstation.

FIG. 5 shows a perspective view of the toggle lever system.

FIG. 6 shows two toggle lever lifting systems which are arranged behind one another in relation to the running direction.

FIG. 1 shows a diagrammatic illustration of one possible embodiment of the packaging machine 59 according to the invention. An underfilm 42 is unrolled from a reel and is first of all heated by way of a heating element. Subsequently, the underfilm is deep drawn in a forming station 43. Said forming station 43 has an upper tool 44 and a lower tool 45. As shown by the double arrow which is intended to symbolize a lifting system, the lower tool 45 can be displaced vertically. Said lifting system has an automatically controlled pneumatic and/or hydraulic drive. As a result, the travel, the speed during the travel and the acceleration can be adjusted at every instant. The speed, at which the tool is moved, is not constant. For example, the tool is accelerated to a pronounced extent at the start of the travel, maintains a high speed as long as possible, in order then to be braked to such an extent that it reaches its end position as gently as possible. The end positions, between which the respective tool moves, can likewise be selected freely. The pneumatic and/or hydraulic drive is controlled by a computer. A person skilled in the art sees that the pneumatic and/or hydraulic drive 46 can also drive the upper tool. As soon as the packaging cavities 58 are formed into the underfilm web 42, they are filled with the material 54 to be packaged. Subsequently, before the packaging cavities pass into the sealing station 48, holes are punched into the underfilm by means of a punching means 56, which holes are required for the gas exchange in the packaging within the sealing station. In the sealing station 48, a top film 55 is sealed onto the underfilm 42 and the packagings are thus closed. The sealing station also has an upper tool 49 and a lower tool 50 which are pressed against one another during sealing. The lower tool 50 is likewise driven by a lifting system 46. A sealing frame which is heated by means of a heating element is situated in the upper tool 49. Finally, the packagings which are then closed are separated in a cutting station 51. The crosscutting means of the cutting station likewise has an upper tool 52 and a lower tool 53, the lower tool 53 in turn being displaceable vertically by way of a lifting system 46.

FIGS. 2-4 show a workstation 43, 48, 51 of the packaging machines according to the invention with an upper tool 44, 49, 52 and/or a lower tool 45, 50, 53. Both tools can be raised and lowered, as shown by the double arrows. The workstation is mounted in the packaging machine by means of the rollers 7 and is therefore arranged such that it can be displaced horizontally along the packaging machine, in particular its frame. For this purpose, the frame particularly preferably has two parallel horizontal rods, between which the rollers are arranged. The upper tool 44, 49, 52 is connected rigidly to a frame 5 by means of the tie rods 6. The tie rods 6 and therefore the upper tool 44, 49, 52 and the frame 5 are mounted such that they can be displaced vertically, their vertical movement being guided on the inner circumference of the hollow body 8, a pipe. The workstation of the packaging machine according to the invention has an automatically controlled hydraulic and/or pneumatic drive with a cylinder 1 and a piston 2. The cylinder 1 is supported on its upper side on a frame 3, on which the lower tool 45, 50, 53 is mounted, while the piston 2 is supported on a transverse rod 4 which is arranged by means of the connecting elements 15 and the screw 21 on a yoke 19 which is connected to the machine frame via the rollers 7. The frame 3 has guide bushings 9 which interact in a guiding manner with the outer circumference of the hollow bodies 8. The frame 3 requires guidance during its up and down movement. One end of the lever 14 is arranged rotatably on the cylinder 1. Its other end is connected rotatably to a further lever 13. This lever 13 is in turn arranged in a rotationally fixed manner on a shaft 16 which is mounted rotatably in the yoke 19. The shaft is driven alternately in and counter to the clockwise direction by the mechanism 13, 14. The part 11 of a lever which has two ends is arranged in a rotationally fixed manner on said shaft 16. At its one end, it has a further lever element 10 which in turn is connected rotatably to the frame 3. The levers 10, 11 form a toggle lever. At its other end, one end of a further lever 12 is mounted rotatably, the other end of which is in turn arranged rotatably on the frame 5. As a result of the rotation of the shaft 16, the toggle lever 10, 11 is transferred from a bent away position into a stretched position and vice versa. The same is true of the lever 12 which is transferred from a substantially vertical position into a more horizontal position as a result of a rotation of the shaft 16. Here, the lever 12 raises and lowers the frame 5 and therefore the rods 6 up and down which are guided on the inner circumference of the hollow body 8. These rods 6 are connected to the upper tool 44, 49, 52 which is likewise lowered and raised as a result. The hollow body 8 is clamped between the frame 18 and the yoke 19 by means of the clamping nut 20. The stroke of the lifting element can be set by way of the setting means 22.

FIGS. 2 and 4 show the lifting system of the packaging according to the invention in a state, in which the frame 3 and therefore the lower tool 45, 50, 53 is situated in its uppermost position and the upper tool 44, 49, 52 is situated in its lowermost position. As a result of a rotation of the shaft 16 in the clockwise direction, the toggle lever system 10, 11 is bent and therefore the frame 3 is lowered and the frame 5 is raised, with the result that the two tools 24, 25 move apart from one another.

FIG. 5 shows the workstation according to FIGS. 1 to 3 in a perspective illustration.

FIG. 6 shows a workstation which has two lifting systems according to FIGS. 1 to 4. A person skilled in the art understands that it can also be more than two lifting systems. The film transport direction is indicated by the arrow. An arrangement of this type of the lifting systems is suitable, in particular, in the case of very large formats, that is to say formats with a very large film advance per cycle. In the arrangement of two lifting systems, it is ensured that the pressure, with which the tools are pressed against one another, is at least substantially identical substantially over the entire tool. Twice the pressing force is available as a result of two cylinders 1. The shafts 16 are oriented parallel to the film transport direction and protrude beyond the frame 5. Said lifting systems are preferably synchronized, particularly preferably positively synchronized. This takes place, for example, by a connection of at least one shaft 16 of one lifting system to at least one shaft 16 of the other lifting system, which shaft 16 is arranged coaxially with respect to the former shaft. The connection can be a coupling which can preferably be released again and is arranged in each case at the shaft ends which project out of the frame 5. Both lifting systems are preferably moved by way of a regulating means. Furthermore, it can be advantageous if the frames 3 and/or the tool carriers which rest on them and on which the tools rest, are connected to one another, in order to achieve as uniform as possible a raising and lowering of the tools over the entire film advancing length.

The lifting system can also be configured in all the exemplary embodiments as in EP 0 569937 or in DE 103 51 567.4.

LIST OF DESIGNATIONS

1 Cylinder

2 Piston

3 Frame

4 Transverse rod

5 Frame

6 Guide rods

7 Rollers

8 Hollow body, guide

9 Guide bushings

10 Part of a toggle lever arrangement

11 Part of a toggle lever arrangement

12 Lever

13 Lever of a mechanism

14 Lever of a mechanism

15 Connecting elements

16 Shaft

17 Nut

18 Frame

19 Yoke

20 Clamping nut

21 Screw

22 Setting means of the stroke

42 Underfilm web

43 Forming station

44 Upper tool of the forming station

45 Lower tool of the forming station

46 Lifting system

48 Sealing station

49 Upper tool of the sealing station

50 Lower tool of the sealing station

51 Cutting station

52 Upper tool of the cutting station

53 Lower tool of the cutting station

54 Material to be packaged

55 Top film

56 Punching means

57 Packaging machine

58 Packaging cavity 

1. A packaging machine, in which at least one tool can be displaced by way of a lifting station into a lowered and into a raised position, characterized in that the lifting system has, as a drive, at least one automatically controlled pneumatic/hydraulic drive.
 2. The packaging machine as claimed in claim 1, characterized in that a pressure of the pneumatic/hydraulic drive is automatically controlled.
 3. The packaging machine as claimed in claim 2, characterized in that it has an absolute travel transmitter.
 4. The packaging machine as claimed in claim 3, characterized in that the absolute travel transmitter knows the precise position of a piston rod of the drive.
 5. The packaging machine as claimed in claim 4, characterized in that the lifting system has a toggle lever.
 6. The packaging machine as claimed in claim 5, characterized in that the tool is a deep drawing mold, a sealing tool and/or a cutting tool.
 7. The packaging machine as claimed in claim 6, characterized in that the movement of the tool can be controlled by a computer.
 8. The packaging machine as claimed in claim 7, characterized in that the tool is arranged together with a lifting station horizontally along the packaging machine.
 9. The packaging machine as claimed in claim 8, characterized in that a tool can be driven by way of a plurality of lifting systems which are arranged next to one another.
 10. The packaging machine as claimed in claim 1, characterized in that the lifting system has a toggle lever.
 11. The packaging machine as claimed in claim 3, characterized in that the lifting system has a toggle lever.
 12. The packaging machine of claim 10, characterized in that the machine is employed in a system that packages foodstuffs between opposing film webs the toggle lever includes at least two lever elements pivotally connected to each other and to a frame of the tool for transferring the lever elements from a bent position to a stretched position, and vice-versa, in response to rotation of a shaft.
 13. The packaging machine of claim 11, characterized in that the toggle lever includes three lever elements pivotally connected to each other and to a frame of the tool for transferring the lever elements from a bent position to a stretched position, and vice-versa, in response to rotation of a shaft, and further wherein the frame of the tool is oriented parallel to the shaft and raises and lowers as the levers go between bent and stretched positions.
 14. The packaging machine of claim 1, characterized in that it includes a lifting system that has a toggle lever that includes three lever elements pivotally connected to each other and to a frame of the tool for transferring the lever elements from a bent position to a stretched position, and vice-versa, in response to rotation of a shaft, and further wherein the frame of the tool is oriented parallel to the shaft and raises and lowers as the levers go between bent and stretched positions.
 15. The packaging machine of claim 12, characterized in that the shaft is oriented parallel to a direction of film transport across the machine.
 16. The packaging machine of claim 13, characterized in that the shaft is oriented parallel to a direction of film transport across the machine.
 17. The packaging machine of claim 14, characterized in that the shaft is oriented parallel to a direction of film transport across the machine.
 18. The packaging machine of claim 1, wherein the machine includes two lifting systems that have their lifting synchronized by connecting at least one shaft of one lifting system to at least one shaft of the other lifting system.
 19. The packaging machine of claim 14, wherein the machine includes two lifting systems that have their lifting synchronized by connecting the shaft of the machine to at least one shaft of a second lifting system.
 20. The packaging machine of claim 19, wherein the machine includes two lifting systems that have their lifting synchronized by connecting the shaft of the machine to at least one shaft of a second lifting system. 